This invention relates to footroll assemblies for continuous casting machines, and in particular to a footroll assembly for a continuous casting machine.
Continuous casting machines are well known in the prior art and include a mold made up of two essentially parallel wide walls (broad face plates) and two essentially parallel narrow walls (narrow face plates) to define a casting passage of rectangular cross section. One of the narrow face plates is adjustable whereby the cross section of the mold, which determines the size of the slab to be cast in the mold, may be varied. The size of the continuous slabs formed by the continuous casting method is substantial as the slabs may be up to 12 inches thick and 100 inches wide. The mold is surrounded by a water jacket which cools the mold.
For a further description of continuous casting molds reference may be had to U.S. patent application Ser. No. 239,530 entitled THERMOCOUPLE FOR A CONTINUOUS CASTING MACHINE, which was filed on Sept. 1, 1988 and which is assigned to the assignee of record of the present application, which description is incorporated herein by reference.
The slab has a very thin skin when it initially forms in the mold. Due to the weakness of the thin skin, the slab must be supported even after it leaves the mold. For this purpose, a series of support zones is conventionally arranged downstream of the mold for continuously supporting the slab as it emerges from the mold. Various types of assemblies have been provided in the past for the support zones. One prior art assembly has provided shoes or grids to support the slab. Another prior art support structure has included a frame having rollers mounted therein wherein the entire frame was resiliently mounted by means of a spring to resiliently support the slab. In this arrangement, the individual rollers mounted in the frame were not spring loaded and the frame was hingedly secured to the continuous casting assembly.
It is important that such support assemblies are resiliently supported as the thickness of the slab may vary to some extent. Furthermore, by providing resilient supporting means, it is assured that the slab is continuously contacted by the support assemblies.
Still other prior art support structures have included individually spring biased rollers mounted to resiliently support the cooling slabs. Yet still other prior art structures have included pinch rollers between which a slab was pinched and wherein the rollers were driven at a predetermined rate to permit the slab to advance therebetween.
A disadvantage of all the above described support assemblies for supporting a continuous cast slab has been that they have been rather complicated and therefore costly to construct. Furthermore, the prior art structures have been difficult to adjust because of their complexity. These prior art structures have included many components each one of which had to be adjusted, thereby causing unnecessary expense in setting up of the casting assembly. Still others of these prior art structures have resulted in too much friction between the slab and the support structure, which is undesirable.
Thus there is a need for a support assembly for a continuous casting machine which is easy to adjust, which is relatively low in cost, and which is subject to little wear of the support structure so that repair of the support structure is required much less frequently than with the above described prior art devices.